Until ten years ago research in epidermal biology was concerned mainly with structural proteins, barrier formation, and the regenerative capacity of the Keratinocytes that kept the structure intact. More recent experimental data reveal the epidermis as an extraordinarily versatile organ. Moreover, by virtue of its mass, its rich vasculature and its contact with the environment the epidermis is theoretically in a unique position to provide chemical signals to the rest of the organism. The keratinocyte is the epidermal cell which has emerged as a source, and sometimes the target, of many of these newly described functions. We think this conference is timely for the following reasons: there is a rapidly increasing body of data concerning novel biological activities of keratinocytes. These data have been narrowly viewed by most investigators but could be cast in a new light if seen from a broader prospective. The proposed conference would bring together investigators with common concerns about technique, methodology and biological significance. Different groups of investigators individually grapple with questions dealing with the significance and function of "activities" specific interest to them. Bringing these investigators together would foster recognition of general principles and approaches that could facilitate the individual's work and stimulate a broader base of interest in these topics. The conference we propose will focus on the keratinocyte and its newly described activities. This will be accomplished first by a critical review of the known biochemical and physiological characteristics of these soluble products and metabolic activities of the keratinocyte. When appropriate, each keratinocyte product or activity will be discussed with regare to a) its role in local homeostasis, b) its effects on other organ systems or cells and c) its structural and functional relationship to similar products or activities from organ systems. The proposed conference will be sponsored by the New York Academy of Sciences and should attract participants and an audience representing a wide range of interests. We anticipate that the meeting should attract cell biologists, protein chemists, immunologists, endocrinologists, cutaneous biologists, clinical dermatologists and broad components of industry. These newly described activities of keratinocytes have significant implications for gaining fresh insights into many cutaneous diseases and may suggest new approaches to therapy, not only of cutaneous diseases but also systemic disease.